Final answer:
Motor proteins are called mechanoenzymes because, unlike other enzymes that only catalyze reactions, they also convert ATP energy into mechanical force, facilitating intracellular movement. The term 'mechanoenzyme' is specific to those proteins that exhibit this dual functionality and is not applicable to all enzymes.
Step-by-step explanation:
Motor proteins are referred to as mechanoenzymes because they convert the chemical energy from ATP into mechanical work, facilitating movement and transport within cells. Unlike most enzymes that solely catalyze chemical reactions, motor proteins such as kinesin and dynein induce physical movement, thus displaying dual roles as both enzymes and mechanical force generators. Mechanically, kinesin promotes anterograde transport of cargo vesicles, such as neurotransmitters, while dynein is responsible for the retrograde movement.
Not all enzymes can be termed mechanoenzymes because the majority are highly specific and accelerate only certain chemical reactions without generating physical movement. Enzymes such as those participating in metabolism or those that are metalloenzymes catalyze reactions by stabilizing transition states and reducing activation energy, but do not perform mechanical work. Hence, the term 'mechanoenzyme' is appropriately reserved for motor proteins that transduce chemical into mechanical energy within the cellular environment.